Piston grinding apparatus



NOV. 7, 1939. c. J. GIVQEEN 2.179.213

P I STON GRINDING APPARATUS Filed Sept. 16, 1938 3 Sheets-Sheet l IN N In s QN E mn gwuo/wbom ELHHENCEJ.GREEN Nov. '7, 1939. c. J. GREEN 2,179,213

PISTON GRINDING APPARATUS Filed Sept. 16 1958 3 Sheets$heet 2 ELHRENCE JEFIEEN imme/:

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Nov. 7, 1939. Q J GREEN 2,179,213

PISTON GRINDING APPARATUS Filed Sept. 16, 1958 3 Sheets-Sheet 3 M6 my ELFIRENCE JE EEN Patented Nov. 7, 1939 ma n PATENT orrms PISTON GRINDING APPARATUS Clarence J. Green, Worcester, Mass, assignor to Norton Company, Worcester, Mass, acorporation of Massachusetts Application September 16, 1938, Serial No. 230,261

9 Claims.

The invention relates to grinding machines, and more particularly to a grinding machine for grinding a work piece of non-circular cross section. Y

One object of the invention is to provide a simple, and thoroughly practical grinding machine foiigrinding a work piece to a non-circular shape such, for example, as a cam, an oval shape on an automotive piston or the like. Another object. of theinventionis to provide a grinding ma-- 7 chine for grinding a work piece of non-circular cross section in which the work piece is. rocked toward and from the grinding wheel .by means j of a rotatable cam. A further object of the inby the cam may be adjusted. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the featuresof construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated. in the following claims.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of a grinding machine embodying the improved grinding attachment; i

Fig. 2 is a fragmentary front elevation, on an enlarged scale, of the improved grinding attachment, showing the driving mechanism;

Fig. 3 is a fragmentary sectional view taken approximately on the line 3-3 of Fig. -2;

Figwiis an end elevation of a modifiedconstruction;

Fig. 5 is a. modification of the arrangement shown Fig. 3; and

Fig. 6 is a fragmentary sectional view, on an enlarged scale, through the pivot stud.

,A cylindrical grinding machine has been illustrated in the drawings comprising a base [0 which supports allongitudinally reciprocable table II onthe usual fiat and V-ways (not shown). The longitudinally reciprocable table II is provided with a motor driven headstock. Iii having a rotatable spindle H which is driven by an electric motor [8. The headstock serves as a driving means for an improved grinding attachment to t be hereinafter described.

A rotatable grinding wheel 20 is supported on a rotatable wheelspindle 2| which is in turn sup- 55'ported on aflwheel slide 22. The wheel slide 22 vention is to provide a grinding apparatus of such 1 a type that the extent of the motion transmitted is arranged to slide transversely on the base iii on a pair of spaced slideways (not shown). The wheel spindle 2i and grinding wheel l9 may be rotated by means of an electric motor l9 mounted on top of the wheel slide 22. The wheel slide 22 is arranged to be moved transversely relative to the base ill by means of a suitable wheel feeding mechanism. The Wheel fee-ding mechanism may be of any well known type such as, for ex ample, that shown in the prior United States patent to C. H. Norton No. 762,838 dated June 14, 1904. This mechanism has not been shown in detail in the present case, since it is not considered to be partof the present invention. For details of disclosure, reference may be had to the above mentioned patent. A manually operable rotatable feed wheel 25 is mounted on the front of the machine base it! and is operatively connected to rotate a feed screw. (not shown) to cause the grinding wheel Zil and wheel slide 22 to be moved transversely toward or from the work supporting table .l l, depending upon the direction of rotation of the feed wheel 25. In the construction illustrated in the drawings, the feed wheel25 may be actuated manually or automatically, as desired. A .mechanically actuated feed pawl 26, such as that shown in the prior patent above referred to, is reciprocated automatic-. ally to advance the wheel at the ends of the reciprocatory stroke of the work table. In the construction illustrated in the drawings, the work supporting table it is arranged to be reciprocated longitudinally relative to the base It! and the grin-ding wheel Zll to traverse the work piece past the operative face of the grinding wheel 20. The table II is provided with a depending rack bar til by which the table may be traversed by a manual or power traverse mechanism, such as that shown in the prior patent above referred to. Reference may be had to the" above mentioned expired patent for details of disclosure not contained herein. A gear 3i meshes with the rack '30 and is mounted on a rotatable shaft 32 which may be rotated manually by means of a gear 33 mounted on the outer end of the shaft 32. A manually operable traverse 'wheel 36 is mounted on the outer end of a shaft 34 and is connected by a gear 35 to rotate the gear 33, the gear 3i, and the rack bar 30 so that the table I I may be traversed longitudinally when 1 desired. l

The table I I may be reciprocated longitudinally by a poweroperated mechanism, such as that shown in the prior patent above referred to. This mechanism may comprise r rotatable power driven shaft 40 which is driven by means of a multiple speed drive contained within a casing M, the details of which have not been shown in the present case since they are not considered to be part of the present invention. For details of this mechanism, reference may be had to the above mentioned prior patent. The rotatable shaft 49 is connected through a reversing clutch (not shown) which is actuated by means of a reversing lever 43. The reversing lever 43 is actuated by reversing dogs 44 and 45 which are adjustably mounted in a T-slot 46 formed in the front edge of the table I I.

In the production of automobile pistons, it is frequently desirable to grind either a portion of the piston or the entire outer surface of the piston to an oval or elliptical form. It is desirable to provide a grinding apparatus which is arranged to oscillate the work supporting spindle toward and from the grinding element so as to produce the desired shape, either oval, elliptical or otherwise, on the periphery of the piston or work piece being ground. For a production grinding machine, such an apparatus may be built into the machine as a permanent part of the machine or may be made in the form of an attachment, as illustrated, which may be readily applied to a standard cylindrical grinding machine.

The improved piston grinding attachment may comprise a frame 59 which is provided with a dovetailed surface 5| which mates with correspondingly shaped surfaces on the table II. A clamping block 52 which is held in place by means of a clamping screw 53 serves to clamp the frame 59 rigidly in position on the work table II. The frame 59 serves as a support for a rock bar 55 which is provided with upwardly extending bosses 55 and 5'! each of which serve as supports for bearings 58 and 59, respectively. Trunnion shafts 69 and 9! are rigidly fastened to the ends of the rock bar 55 respectively and serve as a pivotal support for the rock bar 55. The rock bar 55 is provided with two upwardly extending bearing members 65 and 86 which rotatably support a work supporting spindle 61. A piston supporting head 68 is mounted on the right-hand end of the spindle 6'! (Fig. 2) and serves as a support for the hollow end of a piston 69 to be ground. The rock bar 55 also supports a footstock 79 having a footstock center H which is arranged to engage and support the other end of the piston 69.

A suitable driving mechanism is provided for rotating the work supporting spindle 61 so that the rotative power of the headstock spindle I! may be transmitted to rotate the work supporting spindle 9?. The headstock spindle H supports a sprocket 15 on its outer end which is connected by a link chain 16 with a sprocket 11 which is formed as an integral part of a sleeve 78. The sleeve 18 is rotatably supported on the trunnion shaft 59. The sleeve 18 has formed integrally therewith a sprocket 79 which is connected by a link chain 80 with a sprocket 8| which is mounted on the outer end of the work supporting spindle 61. By mounting the driving sleeve and the integral sprockets T! and 19 on the trunnion shaft 68, the drive between the headstock spindle I1 and the work supporting spindle 9? may be readily accomplished. When the headstock motor !8 is started to rotate the headstock spindle H, a rotary motion is transmitted through the sprocket 15, the link chain 16, the sprocket H, the sleeve E8, the sprocket t9, the link chain 69. the sprockets 8|, to rotate the work supporting spindle 67 and thereby rotate the piston 69 to be ground.

In order to grind a surface on a work piece of non-circular cross section, such as a cam or an oval or elliptical surface on an automotive piston, it is necessary to provide a suitable mechanism for rocking the bar 55 in timed relationship with the work rotation so as to produce the desired and predetermined contour on the work piece being ground. In the preferred construction, a master cam is formed integral with or fixedly mounted on the sleeve 18. The master cam 85 and the sleeve 18 are both rotatably supported on the trunnion shaft 60. In order to transmitthe motion of the master cam 85 to oscillate the rock bar 59, a master cam roller 86 is rotatably supported on a stud 8'! which is in turn supported on the lower end of a pivotally mounted lever 88. The lever 88 is pivotally sup ported on a pivot stud 89 which is secured to a bracket 99. The bracket 99 is in turn adjustably secured to the attachment frame 50 by means of a clamping screw 9| which passes through an elongated slot 92 in the bracket 98 and is screw threaded into the frame 50.

The upper end of the lever 88 is connected by a stud 93 with an arm 94 the other end of which is provided with a bearing surface within which the spindle 61 rotates. It will be readily apparent from this construction that when the headstock spindle I1 is rotated, the power transmitted to the driving mechanism above described rotates the work supporting spindle 61 and the work piece 59 and at the same time rotates the master cam 85 in synchronism with the rotation of the piston 69 to oscillate the work axis towards and from the grinding wheel during the grinding operation.

In order to facilitate adjustment of the mechanism so that the extent of oval or shape may be varied slightly from that of the master cam 89, an adjustment is provided in the connection between the master cam and the spindle 61. As illustrated in the drawings, the lever 88 is provided with an elongated slot 95 by means of which the fulcrum point of the lever 88 may be adjusted as desired. It is desirable to maintain the axis of the stud 81 supporting the follower roller 86 in the same horizontal plane with the axis of rotation of the master cam 85 and the trunnion shaft 69 during any adjustment of the lever arms. Consequently, if it is desired to change the adjustment of the mechanism, the bracket is adjusted vertically up or down, and the fulcrum stud 89 is adjusted correspondingly so as to vary the lever arm between the stud 81 and the fulcrum' stud 89 and also between the fulcrum stud 89 and the stud 93. If the fulcrum stud 89 is positioned midway between the stud 8'! supporting the follower roller 89 and the stud 93, then the piston 99 being ground will be rocked by an amount as governed by the rise and fall of the master cam 85.

As illustrated, the master cam has been shown as of a non-circular contour for producing a noncircular contour on the piston 69 being ground. If it is desired to vary the contour of the work piece slightly from that of the master, then the bracket 99 and the fulcrum stud 89 may be adjusted vertically to change the lever arm relationship of the lever 88 so as to increase or decrease the rocking movement of the rock bar 55 for each rise and fall of the cam and thus vary the shape produced upon the piston 69.

For grinding certain types of work, such as av equally spaced, identically shaped v-lobes: projecting therefrom, it maybe desirable to utilizea single lobe, master cam, such asfor .examplelthat shown inFig. 5, to transmit a rocking motion by the same projection or lobe. on the master cam. If there are two identically shapedlobes on the shaft or work piece being-groundy=then the sprocket and chain driving connection'between thesleeve ill and the spindle 6'! Willbea twoqto one reduction, so that the master cam 85a will rotate twice a while the spindle M is rotating-once. 1A master cam'havinga single lobepis much less expensive to manufacture thanone having, .for example, two, three ormore lobes; The shape of the single merely by utilizing the proper gearing between the master cam and the .produ'ctoam or'work piece. It may be desirable when grinding certain types of work to locate the master cam 50" that it rtates about an axis which is not concentric with i the axis ,of the trunnion shaft 60. Such an arrangement of parts has been. illustrated in the modification shown in Fig. 4. A-master camshaft Mil is supported in an upwardly extending-bracket Bill formed integral with the frame 50. The master camshaft Hill supports .a master cam I02 which is engaged by a follower roller I03. The follower roller m3, is supported-bye stud Hi4 at the lower end of a lever lllt'a. The lever |05is pivotally supportediby an adjustable fulcrum stud Hit; which is fixed to'a bracket I01. .The bracket lil'l isadjustably mounted .onlan upwardly extending portion Hill of the frame 5|] by means of a clamping'screwdllil. i-The upper end of the lever W5 is connected by a-stud H0 with one end of a link i l l the other-endaof whichis'connected by a stud H2 'withua, short connecting rod- H3 the other end of which surrounds the spindle 61. 1 The master cam M12 is driven bya link chain i it? from a sprocket i Ifi WhiCh is: formed'integral with or .fixedly mountedonthesleeve 61. -A

sprocket H7 is mounted on 171180111381 end of the master camshaft Illllso that whenthe sleeve 67 motion is transmitted by the sprocket H6, the link chain N5, the sprocket Ill, to rotate the master camshaft Hill and the master cam I02 so as to transmit a rocking motion to the rock bar 55 through the mechanism above described.

The operation of this apparatus is readily ap parent from the foregoing disclosure. Assuming the adjustments of the various parts of the mechanism have been previously made, the work piece, such as a piston 69 (Fig. 2), is placed in position on the head stock supporting member 68 and the footstock center i I. The grinding wheel is then started rotating and a rotary motion is desired to slightly change the long and short axis of the oval or ellipse produced on the piston, then the braoketilt may be adjusted vertically and the fulcrum stud 89 may be adjusted in a like manner to vary the oscillating movement transmitted to the rock bar 55 by the master cam 85.

Itwill thus be seen'thatthere has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be to the rock bar 55 so that. each of the projecting I lobes on theworkpie'cebeing ground is formed made of the above invention and as many changes might be made in the embodiment above set forth,

' it is to be understood that all .matter hereincircular workpieces, a rotatable grinding wheel,

apivotally mounted 'rockbar, a rotatable work support thereon including a rotatable spindle andla pair of opposed aligned work supporting accurately formed lobe may accurately reproduce a plurality of, identical lobes :on the work piece and afollower which are arranged to rock said bar to cause said workcenters to approach and recedefrom said grinding wheel, and driving con- -nections synchronously to rotate said spindle and master cam, said connections being arranged so that the master cammayibe rotated at a different speed from the work spindlewhereby a single 'lobedmaster. cam. may be-utilized to produce a multiple lobed work piece. 1

2. In a grinding machine for grinding noncircular' work pieces, a pivotally mounted rock bar, a rotatable work, support thereon including a rotatable spindle and a' pair of. opposed aligned work supporting centers, a pair of opposed aligned .trunnions to supportsaidrock bar, a rotatable driving sleeve on one. of said trunnions, a rotatable master cam and a follower, driving connections between said sleeve and said spindle to rotate said spindle, and driving. connections between said sleeve and said master cam to rotate the master camsynchronously with said spindle.

3. In a grinding machinefor grinding noncircular work pieces, a pivotally mounted rock bar,

a rotatable work support thereon including a rotatable spindle andaa pair of opposed aligned work supporting, centers, 2. pair of opposed aligned trunnions to supportfsaid rock bar, a rotatable driving sleeve onone of. said trunnions, a rotatable mastercam and a follower, and driving connectio-nsibetween said sleeve and said spindle and between said sleeve and master cam syn.- chronously to rotate said spindle and master cam, said driving connections being arranged so that the spindle may be rotated at a different speed from the master cam' so that a single lobe master cam will grind a multiple lobe work piece.

, 4. In a grinding machine for grinding noncircular work pieces, a pivotally mounted rock bar, a rotatable work support thereon including a rotatable spindle and a pair of opposed aligned work supporting centers, a pair of opposed aligned trunnions to support said rock bar, a rotatable driving sleeve on one of said trunnions, driving connections between said sleeve and said spindle to rotate said spindle and work piece, a master cam on said sleeve, a pivotally mounted lever, a follower roller on one end of said lever, a link connecting the other end of said lever with the spindle, and an adjustable pivot stud for said lever which is located between said follower roller and said link whereby the lever arms may be adjusted to vary the extent of rocking movement of the work to vary the contour produced thereon.

5. In a grinding machine for grinding noncircular work pieces, a pivotally mounted rock bar, a rotatable work support thereon includin a rotatable spindle and a pair of opposed aligned work supporting centers, a pair of opposed aligned trunnion shafts to support said rock bar, a rotatable driving sleeve on one of said trunnions, gearing connections between said sleeve and said spindle to rotate the spindle and work piece, a master cam on said sleeve, a pivotally mounted lever, a follower roller on the lower end of said lever, a link connecting the upper end of said lever with the spindle, a pivot stud for said lever located between said follower roller and said link, an elongated slot in said lever to facilitate adjustment of said stud relative to said lever, a bracket supporting said stud, and means to adjust the position of said bracket so as to vary the position of said stud and thereby vary the distance between said follower and said stud and said stud and the link so as to vary the extent of rocking movement of the work to vary the contour produced thereon.

6. A grinding attachment for grinding noncircular work pieces adapted for use on a cylindrical grinding machine having a rotatable headstock spindle, an attachment frame arranged to be clamped on said machine, a rock bar pivotally supported on said frame, a rotatable work support on said bar including a rotatable spindle and a pair of opposed aligned centers, a pair .of opposed trunnion shafts on said bar pivotally to support the rock bar on said frame, a rotatable driving sleeve on one of said trunnions, gearing connecting said sleeve to rotate said spindle whereby the work spindle rotates at half the speed of the sleeve, a master cam on said sleeve having a single lobe thereon, a master cam follower, and adjustable lever connections between said follower roller and said spindle whereby the rock bar is oscillated when the cam is rotated, said driving gearing and single lobe cam being arranged to oscillate the rock bar twice for each rotation of said spindle whereby a single lobe cam will produce diametrically opposed lobes on the work piece.

7. In a grinding machine for grinding nonoircular work pieces, a pivotally mounted rock bar, a rotatable work support thereon including a rotatable spindle and a pair of opposed aligned work supporting centers, a pair of opposed aligned trunnions to support said rock bar, a rotatable driving sleeve on one of said trunnions, driving connections between said sleeve and said spindle to rotate a work piece mounted thereon, a rotatable master cam which is arranged to be rotated by said sleeve, and adjustable lever connections including a follower roller whereby the motion of said cam is transmitted to oscillate said rock bar so as to produce a predetermined contour on a work piece.

8. In a grinding machine for grinding noncircular work pieces, a pivotally mounted rock bar, a rotatable work support thereon including a rotatable spindle and a pair of opposed aligned centers, a pair of opposed aligned trunnions to support said rock bar, a rotatable driving sleeve concentric with one of said trunnions, driving connections between said sleeve and said spindle to rotate a work piece supported thereon, a rotatable master cam, driving connections between said sleeve and said master cam to rotate the latter, a rotatable follower roller, and adjustable lever connections between said follower roller and said spindlewhereby motion of said cam is transmitted to oscillate the spindle and rock bar during rotation of said spindle to produce a predetermined contour .on said work piece.

9. In a grinding machine for grinding noncircular work pieces, a pivotally mounted rock bar, a rotatable work support thereon including a rotatable spindle and a pair of opposed aligned centers, a pair of opposed aligned trunnions to support said rock bar, a rotatable driving sleeve concentric with one of said trunnions, driving connections between said sleeve and said spindle to rotate a. work piece supported thereon, a rotatable master cam, driving connections between said sleeve and said master cam to rotate the latter, a rotatable follower roller, adjustable lever connections between said follower roller and said spindle whereby motion of said cam is transmitted to oscillate the spindle and rock bar during rotation of said spindle to produce a predetermined contour on said work piece, and means to adjust said lever connections whereby the extent of oscillation of said spindle and rock bar may be varied to vary the shape produced on the periphery of the work piece.

CLARENCE J. GREEN. 

